.efu is Encryptafile Public Key File
Key Features: .EFU File Extension
What is an .EFU file?
Public Key used to authenticate an encrypted Encryptafile (.EFL) file; contains a hexadecimal representation of the public key; made available to the public and used along with the Private Key (.EFR) file to verify a digitally signed file.
The length of a public key file must be greater than or equal to 16 bits, and less than or equal to 7128 bits.